I'm sure we're a pretty small market compared to bicycling, motorcycling, and other sports, but how sweet would it be to have your vario and GPS info displayed on heads-up-display? This Israeli company is making a pair of heads-up-glasses for cycling:

It'd be nice to have something like these as purely a heads-up display (i.e. your vario/GPS does all the sensing and processing and just sends that data to the glasses to display). A small controller (like the Raptor glasses use, mounted on your base tube), would let you scroll through different screen configurations and/or data fields (including your own custom-designed screen configurations).

I'm waiting for glasses like this that can plug (or use WiFi) into an iPhone or Android phone. Then any app could send a left and right image to each corresponding eye. Then you could get some awesome augmented reality with a vario app. Imagine seeing airspace projected into your field of view or a breadcrumb trail showing your flight path. All of this in addition to basic vario data.

I think audio for the vario would be what I'd still want. HUD screen pages would be there for other data like L/D, fpm, agl, bearing, airspace, etc to keep the display less cluttered for the majority of a flight. S2F could be colors like green speed up red slow down or some different colors maybe better idk but that's all I'd want in view generally.

Yup, if you had some kind of screen designer app/program, you could place your data fields towards the edges of the "screen" to keep thing unobstructed. Numbers or indicators could change colors depending on what the data is doing. You could have digital and/or simulated analog gauges. Audio settings could be configured in there as well.

I found a company that is doing an aviation specific smart-glasses system:

Some of their overlays cover up a bit too much of your real view in my opinion, but hopefully that's something that you could configure to be less intrusive. Also, the whole AR system would probably be a bit much for hang gliding - I'd be happy with some basic data fields for now.